I've got a CS-40M and the full service manual - I'll have a look tonight and see what i can find.

Good luck.

PS, looking at your pics the compartment for the memory back-up battery is missing. It should fit into that hole in the base. At least a couple of those wires will go there. I'll check these connection for you asap.

The thicker, taped-up pair of black/orange goes to the battery compartment. Black is ground, Orange is positive. I'll check my files later to find out what kind of batteries you need. They look to be AA-size, probably around 1.4V each, two of. The outer case of the battery compartment should also have a tab for connecting an earth lead (the thick green one)

It looks like you're missing the headphone jack. Taking the thin pair of wires, Orange is tip, Red is ring; presumably the large green earth cable was also providing ground for the socket.

Lastly, the thin orange/black pair with the 2-pin connector: in the whole service manual, I can see only one mention of it - it's labelled "BC". But it's not connected to anything in my CS, and there's no sight of it in the schematics.

Well, the previous owner should be shot... That's a very reliable synth, but those CMOS chips are a problem to replace. Have you checked out old crow's CS-80 site? Lot of info there that would be relevant.